1. Field of the Invention
The disclosed subject matter relates generally to the fabrication of semiconductor devices and, more particularly, to using sidewall image templates for directed self-assembly materials.
2. Description of the Related Art
Many technological applications require the ability to pattern precise structures with increasingly smaller pitches. Existing optical lithography is capable of high-throughput processing, but the patterning pitch of a single optical lithography step is limited. A challenge for lithography is to devise tools, materials and processes that can reliably, efficiently and quickly pattern structures with smaller dimensions, reduced pitch or varied pitches.
Directed Self-Assembly (DSA) lithography is a materials-based approach that relies on the phase separation of certain polymeric materials. A basic DSA process consists of coating a polymeric material on a substrate over a previously formed guide pattern. The guide pattern is typically formed by an optical lithography process. The polymeric self-assembly material contains two (or more) chemical components that have carefully controlled size. These so-called A and B components can be bonded together into polymer chains known as diblocks. Immediately after coating, the A and B components are relatively disordered, however, these components (A, B) can be induced to separate into distinct phases and thereby form features with a characteristic pitch that is defined by the chemical composition. By coating this polymer on a substrate with a pre-formed guide pattern, it is possible to “interpolate” the features between the elements of the guide pattern and reduce the pitch by a factor of 2-40 relative to the guide pattern.
While DSA has shown promise in creating large areas of straight line/space patterns with constant pitch, it is difficult to pattern lines of varying pitch and/or dimensions using DSA technology. Such structures are useful for semiconductor device applications.
The present application is directed to using sidewall image templates for directed self-assembly materials so as to eliminate or reduce the effects of one or more of the problems identified above.